The invention relates to the protection of an object against falsifications and/or for purposes of authentication and/or in order to guarantee its intactness, by means of a thin protective film, in particular a transparent film, of synthetic material which is designed to be glued onto the surface of an object.
The object can for example be an official document (passport, identity card, driving license etc), which contains variable details (surname, first name, address etc of the holder), to be protected against attempted falsification. In this case, the film is transparent. The object can also be an official document, packaging, or any product or article on which the presence of the film guarantees the authenticity of the object and/or its intactness (i.e. the fact that it has not previously been used, or consumed, or tampered with). The film is then not necessarily transparent, but incorporates security patterns which are impossible or difficult to reproduce (hologram, anti-photocopy printing, pigments which are invisible in visible light, but visible in invisible light, etc).
Attempted falsification, forgery or violation of objects which are protected by a film consists mostly of ungluing the film by means of a solvent used to dissolve the adhesive which keeps the film glued onto the object, without damaging the object, or the text it bears, or, preferably, the protective film.
Throughout the text, the term xe2x80x9cadhesivexe2x80x9d designates generally any composition which has the property of adhering in certain conditions, and therefore includes not only self-adhesives (or pressure-sensitive adhesives), but also adhesives which can be reactivated or sealed by heat (or hot glued), and glues in general (mono- or multi-component).
The solvents used by defrauders can be aqueous polar solvents (water, detergent- or alcoholic- aqueous solution etc), or non-aqueous polar solvents (acetone, alcohol, etc), or non-polar solvents (hydrocarbons such as petrol, ether, white spirit etc).
A protective film is already known (FR 2,675,742), comprising patterns printed with an ink composition which incorporates at least one pigment which is soluble in hydrocarbons.
However, pigments of this type are rare, and do not make it possible to obtain all the security patterns required. In particular, they have low variety of colors and effects. Consequently, their presence can be detected by observation by informed defrauders.
Compositions of reagents are also known, which can be incorporated into papers, and are normally colorless, but react in contact with a solvent such as to become colored.
In general, reagents to polar solvents are colored black, and reagents to non-polar solvents are colored blue. These reagents therefore make it possible to reveal an attempt to attack the paper by a solvent. However, they have several disadvantages. Firstly, their reactivity decreases over a period of time until it disappears, such that they cannot provide long-term protection. Secondly, the reaction of coloring in contact with the solvents implements chemical processes which are poorly controlled, and the reactivity of the reagents is not constant on the basis of production, such that it is never certain that the quantity of reagents incorporated in the paper when it is produced actually makes it possible to trigger the reaction. In other words, these colored reagents cannot be used with great reliability. Thirdly, these reagents react in general with the adhesive compositions, which themselves contain solvents, plasticisers and wetting agents, such that they are not compatible with protection by gluing a film onto the paper, since a reaction is triggered during application and setting of the adhesive, and even after the adhesive has set.
Compositions of inks are also known which incorporate reagent pigments which change color in contact with a solvent. However, in this case also, these reagent pigments react with the adhesive compositions. In addition, these pigments are also limited in number and shades, such that they have a low variety of colors and effects, and can be detected by an informed observer.
The object of the invention is thus to eliminate these disadvantages, by proposing a method and a product for protection of an object by means of a film glued onto a surface of the object, wherein attempts to unglue the film by attack by solvents can be revealed reliably and irreversibly over a long period of time (without a substantial decrease in the efficiency of the detection in the long term), and in a manner which is compatible with the gluing of the film onto the object.
The object of the invention is also to prevent this protective function from being detected in advance (by revealing attempts to unglue the film) in the protected object, in particular by simple visual observation by informed defrauders.
The object of the invention is also to permit production of security imprints by means of an ink composition which incorporates this function of protection by revealing attempted attacks by polar and/or non-polar solvents, and which makes it possible to obtain all the patterns, colors and effects required, as in the case of a conventional ink.
The object of the invention is also to propose a method for production of a product for protection according to the invention, and an object protected by a method for protection according to the invention.
The invention also makes it possible to achieve these aims simply and economically, in particular by silk-screen printing.
For this purpose, the invention relates to a method for protection of an object in which a thin protective film of synthetic material is glued onto a surface of the object, by means of a layer of adhesive interposed between the said surface and the object, in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, wherein, between the film and the said surface of the object, there is interposed at least one imprint, known as security imprint, produced by means of an ink composition comprising at least one pigment and a bonding agent which can be hardened by drying in air, designed to form a layer of imprint which is solid after it has dried, and incorporating at least one agent, known as a soluble agent, which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried, in any polar and/or non-polar liquid solvent which can permit ungluing of the adhesive when it is placed in contact with this adhesive after gluing, the quantity of soluble agent(s) in the bonding agent being designed such the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
The invention also extends to a method for production of a product for protection of an object comprising a thin protective film of synthetic material, which is designed to be glued onto a surface of the object by means of a layer of adhesive interposed between the said surface and the object, in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, characterized in that on an imprint support there is provided at least one imprint, known as a security imprint, with an ink composition comprising at least one pigment and a bonding agent which can be hardened by drying in air, designed to form a layer of imprint which is hard after it has dried, this bonding agent incorporating at least one agent, known as a soluble agent, which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried, in many polar and/or non-polar liquid solvent which can permit ungluing of the adhesive when it is placed in contact with this adhesive after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, and reveals any attempt at ungluing by means of at least one solvent, the imprint support being designed to permit interposition of the security imprint between the film and the said surface of the object.
The invention also extends to the product obtained by the method for production according to the invention. It thus also relates to a product for protection of an object comprising a thin protective film of synthetic material, comprising a layer of adhesive such that it can be glued onto a surface of the object, in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, and a security imprint produced by means of a solid imprint composition, containing at least one pigment in a bonding agent, characterized in that it comprises at least one security imprint produced with a solid imprint composition comprising at least one pigment and a hardened bonding agent incorporating at least one agent, known as a soluble agent, which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried, in any polar and/or non-polar liquid solvent, which can permit ungluing of the adhesive when it is placed in contact with this adhesive after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
The invention also extends to the object protected by a method for protection according to the invention. It thus also relates to an object comprising a thin protective film of synthetic material glued onto one of its surfaces, by means of a layer of adhesive interposed between the said surface and the object, in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, characterized in that it comprises, interposed between the film and the said surface of the object, at least one imprint, known as a security imprint, produced by means of a solid imprint composition, comprising at least one pigment and a hardened bonding agent, incorporating at least one agent, known as a soluble agent, which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried,din any polar and/or non-polar liquid solvent which can permit ungluing of the adhesive when it is placed in contact with this adhesive after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
In addition, advantageously and according to the invention, a method for protection, a method for production, a product, and an object according to the invention are characterized by all or part of the following characteristics:
at least one soluble agent is selected from amongst the acrylates of alkyls, the methacrylates of alkyls, their polymers and their copolymers;
the bonding agent incorporates a polymethacrylate of isobutyl as a soluble agent;
an ink composition is used in which at least one soluble agent is formed from a chemical compound which has a low molecular weight, in particular lower than 5000, such as to be able to be soluble in polar and/or non-polar solvents;
in order to produce a security imprint, a bonding agent is used which comprises a liquid solution, comprising a volatile solvent which dries in air, and at least one soluble agent;
in order to produce a security imprint, a silk-screen ink base is used, comprising at least one agent which is soluble in solution, in a solvent containing at least 10% by volume, and in particularly mostly, propylene carbonate;
in order to produce a security imprint, use is made of a bonding agent comprising a diluting wash which is fugitive in water;
a security imprint is produced on one surface of the film, which is then glued onto the object;
the film is glued by means of a layer of adhesive which is previously imprinted onto the film;
a security imprint and an imprint of a layer of adhesive are produced on a single surface of the film;
a layer of adhesive and a security imprint are imprinted such that they do not overlap one another;
a layer of adhesive is imprinted on the film by silk-screen printing, covering a security imprint previously produced on the film;
a security imprint is imprinted on a layer of adhesive without initial instantaneous adhesion, previously produced on the film;
a security imprint is discontinuous, and is in the form of a raster or patterns;
a security imprint is continuous, and extends opposite the entire surface of the film;
the film is selected from amongst a single-layer film, a multi-layer film comprising superimposition of layers imprinted by silk-screen printing, varnish and/or inks, and a multi-layer assembly of superimposed synthetic materials;
the film is formed from at least one synthetic material selected from amongst a polyurethane, a polyester, a polystyrene, a polypropylene and a polyethylene;
the film has an overall thickness of between 5 and 500 microns;
a security imprint is produced by silk-screen printing;
at least one pigment is used, selected from amongst the pigments which are visible in visible light, and pigments which are invisible under lighting in visible light, and photoluminescent under lighting by at least one non-visible source of light; the pigment can be or can not be soluble, like the soluble agent(s) of the bonding agent, in the said solvents which can unglue the adhesive;
a security imprint is interposed between the film and a layer of adhesive which is associated with the said surface of the object;
a security imprint is interposed between a layer of adhesive which is associated with the film and the said surface of the object; and
a security imprint is incorporated in a layer of adhesive, without mutual overlapping of the security imprint and the layer of adhesive.
The invention also relates to a method for protection, a method for production, a product and an object, characterized in combination by all or some of the characteristics described previously or hereinafter.